This type of construction machine generally has a crawler traveling body which has an idler wheel (a driven wheel) at the front end portion of its longitudinally long traveling frame and a drive sprocket (a driving wheel) at the rear end portion of the same, and in which a crawler (an endless track) is wrapped around the idler wheel and the drive sprocket. In this traveling body, the drive sprocket is configured in such a manner that: a hydraulic drive motor is used as a driving source thereof; a′ motor housing that includes the hydraulic drive motor therein and has mounting portion to be fixed to laterally inner side of the traveling frame; a sprocket housing rotatably supported on the laterally outer side of the motor housing; and a sprocket that comes into engagement with the crawler is integrally provided in the sprocket housing. Once the drive motor is driven, the sprocket is rotated by the drive motor to drive the crawler back and forth, and thus the construction machine can be traveled.
In this traveling body, a space is provided between the motor housing functioning as the mounting portion and the sprocket housing functioning as a rotary portion, so as not to create a sliding friction therebetween, and a floating seal is provided between the inner circumferential surfaces of the motor housing and the sprocket housing to close the space.
This type of construction machine is usually used in workplaces with severe conditions. In such workplaces, foreign matters such as sediments may reach the floating seal through the space between the motor housing and the sprocket housing, soon resulting in wear of the floating seal. Wear of the floating seal leads to problems not only the inhibition of smooth rotation of the sprocket housing but oil leakage.
Providing an additional protective cover to the space between the motor housing and the sprocket housing to prevent the entry of foreign matters such as sediments into this space has been proposed (see Patent Documents 1 and 2, for example).
Patent Document 1: Japanese Utility Model Application Publication No. H6-51082
Patent Document 2: Japanese Patent Application Laid-open No. 2013-189042